1. Field of the Invention
This invention relates to the field of a soldering structure, and more particularly, to the soldering structure containing a Sn—Co—Fe intermetallic compound layer having a thickness less than 10 μm.
2. Description of the Prior Art
In general, Co is effective in blocking Cu diffusion and capable of being the potential diffusion barrier layer material in flip chip packaging. However, its reaction with solders is much intense. The fast reaction rate between solders and Co based diffusion barrier layers result in thicker intermetallic compounds. The disadvantage of the soldering structures having a thicker intermetallic compound is that too thick intermetallic compound is detrimental to the soldering structure or soldering joints. Hence, it is important to reduce the reaction rate between solders and Co based diffusion barrier layers.
Based on the aforementioned, the important target of current industries is to develop a soldering structure having a thinner intermetallic compound. In particular, the soldering structure comprises a Co based diffusion barrier layer and a unique intermetallic compound.